I see, you want a functional language with first class concurrency, which also values high single thread performance and low memory footprint? I don't know of

I see, you want a functional language with first class concurrency, which also values high single thread performance and low memory footprint? I don't know of many, I'm thinking Julia JoCaml or Red maybe a little. but their approach currently requires manually annotating functions with "async," creating an incompatible calling convention with existing Rust code. Can this be avoided? How else?